This invention relates to plastic article shaping or the like and specifically to a tire building drum or mandrel and apparatus associated therewith.
In the building of a radial tire, a plurality of layers or plies of stock are positioned upon a rotatable drum or mandrel until such time as the material on the drum is forced to assume a torroidal shape. The cap belts and base stock are then placed upon the tire body after which they are subjected to a stitching operation. The then finished uncured green tire is ready for removal from the building drum or mandrel and the delivery of same to a storage or handling area or to a conveyor for subsequent manufacturing steps, such as vulcanizing. Uncured tires, especially truck tires and off-the-road machinery tires, by virtue of their weight and physical characteristics, are not only delicate but also cumbersome to the point that manually handling said tires becomes a laborious task.
The strength and ability of a green tire to withstand physical abuse is minimal to the extent that said tire is not capable of supporting its own weight when placed upon a planar surface. Thus, any surface that is adapted to receive green uncured tire bodies must be of either a flexible nature or have a dished or contoured surface that can readily conform to that of the tire or tires being moved. Furthermore, the physical properties of green rubber are those of a sticky, easily distorted plastic substance which will flow, become distorted, adhere to foreign substances and permit foreign bodies to become embedded therein.
In the tire building and processing field, the usual practice is to have the machine operator effect the removal of the tire and the delivery of same to a handling or storage area or to place same upon a conveyor to permit subsequent manufacturing steps or operations. Such a procedure does not entail any undue hardship or burden upon the operator as long as small size tires for passenger cars are being manufactured. In the manufacture of large truck tires, especially the all steel radial variety, as well as large off-the-road machinery tires, it has been customary to resort to the use of slings and cranes. The use of a sling, in combination with a hoist or crane, is time consuming and the utilization of same as a supporting means still requires great physical exertion on the part of the operator in effecting the manipulation and removal of such a tire from the building drum and if dropped, the tire becomes badly distorted due to its ductility and if moved in contact with the floor, said tire's surface will become contaminated with foreign matter.